Prior art turntables are generally fixed in size for a particular application, so they are specifically designed and manufactured for just one set of customer needs (i.e., built to a specific turntable diameter and with one or more specific loading capacities). For instance, when underwater power or signal cables need to be laid underwater for the transmission of electric power or communications signals from one ocean or lake coast to another, it is often done by the mounting of turntables that contain such cables onto the deck of a ship or barge and then as the ship or barge leaves one coast it lays out those cables that are unspooled from the turntable. Once the cable has been laid underwater for that particular project, the turntable often has no other uses unless there is another project that requires a turntable having a similar diameter and loading capacity, which is not very often, resulting typically in the immediate obsolescence of that turntable.
Another common temporary turntable application is where a temporary turntable is required for a construction jobsite to allow for the turning of construction vehicles (such as dump trucks, concrete trucks and other similar vehicles) in portions of the construction site that have constrained space and where it is difficult for the vehicles to turn around; in such situations, a general contractor may want to install a temporary turntable in those areas of the construction site that temporarily have such constrained spaces.
For customers needing to purchase a turntable for one of these projects, the turntable can be very expensive (since it is often large and made out of steel to accommodate very large loads) and its cost cannot be easily spread out amongst other projects and other customer uses if those other projects and customer uses require different turntable sizes or load capacities. For some customers, they have attempted to address this problem by having an existing turntable be modified after its initial use to accommodate another project by hiring one or more other firms to develop a design for the different sizes and load capacities needed and then to manufacture and ship the parts needed for such modifications, and to extensively cut up and modify the existing turntable for such modifications (which can be very expensive and time-consuming). In some cases, the modified turntable may not work as well as a turntable that was designed and built from scratch, since the modifications may require extensive cutting, drilling, welding, grinding and fit-up work be done between new and old parts that may not mate up well with one another.